1. Field of the Invention
The present invention relates to dental instruments and to a method of operating on teeth or dental workpieces. In another aspect, the present invention relates to improved dental instruments for teeth or dental workpieces having a contact surface comprising a coating of dehydrogenated diamond-like film having both amorphous and microcrystalline atomic structures and to a method of operating on teeth or dental workpieces utilizing such improved instruments.
2. Description of the Related Art
Many different types of dental instruments are utilized in the practice of dental medicine. For example, dental burs are used to drill into teeth, and to shape internal and external tooth surfaces. Endodontic drill files are utilized in root canal dentistry to clean out the root canal. Scaler dental instruments are utilized for treating periodontal disease. Dental workpieces, such as inlays, onlays, crowns and bridges are operated upon utilizing cutting discs or dental burs. Models of patients' mouths are operated upon, requiring cutting of stone or plaster.
It is important that these dental instruments be sharp and hard to operate properly upon teeth, dental workpieces and models.
Generally, dental instruments are operated at very high speeds, generally in excess of 100,000 rpm, and particular care is taken with lubrication and cooling. However, in spite of advancements in dental instruments and dental procedures, the patient will still be traumatized to a certain extent.
Improvements in the durability of dental instruments would increase patient comfort, because a dental instrument that remains sharp longer will generally in the long run be less traumatic. To the dentist, a more durable dental instrument would lessen the need to change the instrument during a procedure because of dulling of the instrument.
As a consequence of sharper instruments, drilling and grinding speeds can be shortened, vibration effects from a non-uniformly worn dental instrument can be reduced, and to these improvements can additionally be added improved lubricity and heat transfer properties. Unfortunately, inherent in conventional efforts to make a sharp and durable dental instrument is that these materials tend to be brittle, and crack and break. Breakage during a dental procedure represents danger to the patient. A piece of the instrument may come loose and not be readily retrievable, or may jam in a tooth crevice, requiring sacrificing some of the tooth. These tendencies may be countered not only by maintaining sharpness longer, but also by providing toughness as well.
Not surprisingly, there have been many attempts in the prior art to improve the durability of dental instruments.
U.S. Pat. No. 4,190,958, issued Mar. 4, 1980 to Martin et al., discloses an endodontic drill file having a drilling surface coated with diamond particles.
U.S. Pat. No. 4,466,795, issued Aug. 21, 1984, to Plischka, discloses a helocoidally grooved dental bur having a working surface covered with diamond particles.
U.S. Pat. No. 4,681,541, issued Jul. 21, 1987 to Snaper, discloses a dental bur having a metal nitride or carbide layer applied over diamond particles.
U.S Pat. No. 4,731,019, issued Mar. 15, 1988 to Martin, discloses a scaler dental instrument that is coated with diamond particles.
U.S Pat. No. 4,895,146, issued Jan. 23, 1990 to Draenert, discloses a surgical bone grinding instrument having a coating of diamond particles in size of about 30 to about 250 microns.
While the use of a coating of diamond particles on the contact or working surface of a dental instrument represents an improvement over conventional dental instruments, such coatings still need improvement. These diamond particles are generally embedded into a relatively soft substrate. As the substrate erodes, the diamond crystals are lost. While a coating such as at disclosed in the '541 Snaper patent will lengthen the life of such coatings of diamond particles, the particles are still susceptible to being dislodged.
In addition, during dental operations, there is a build up of ground material in the grooves of dental burs, disks, drills and bits. This build up reduces function until the bit must be discarded for a new one since it is presently not practical to clean out these grooves.
Therefore, the need exists in the dental instrument art for a dental instrument with a contact surface with improved durability. There also exists a need in the dental instrument art for a dental instrument that can be more easily cleaned of the build-up of ground material.